"The Light" sounds like railroad-ese for "Long Island Lighting Co." Easier to say than "the power plant" or "Long Island Lighting"...
Thus, ...the coal train used the trailing point crossover east of Long Beach Road to shove across into "The Light" probably means that they used the crossover to get onto the proper main in order to access the switch to shove into the LILCO plant.
Thus, ...the coal train used the trailing point crossover east of Long Beach Road to shove across into "The Light" probably means that they used the crossover to get onto the proper main in order to access the switch to shove into the LILCO plant.